In a cellular communication system using spread spectrum technology, such as Code Division Multiple Access (CDMA), the spectrum is divided into 40 frequency bands. The 40 bands are divided between wireline and non-wireline applications, generally assigning 20 bands to each. The 20 bands are equally divided with 10 bands used for forward communication, with the base site as the transmitter, and 10 bands used for reverse communication, with the mobile as the transmitter. Each band is typically 1.2288 MHz wide and will handle multiple users simultaneously.
In this description, calls and users are used interchangeably. A band that supports X users supports X calls. The capacity of a band in number of users refers to full rate (9600 baud) users unless otherwise stated. A band that supports X full rate (9600 baud) users, will support 2X half rate (4800 baud) users, or 4X quarter rate (2400 baud) users. The band will also support a certain number of variable rate users (9600, 4800, 2400, or 1200) with the exact number of users dependent on the amount of time spent at each baud rate.
In operating at system capacity, accurate mobile transmit power control is very important. Mobile power is controlled from the base station by transmitting power control data to the transmitting mobiles. The base station can direct each mobile to increase or decrease its transmitting power, typically in preset increments (e.g. 0.5 dB), through use of a Frame Error Rate (FER) measurement and an E.sub.b /N.sub.o (signal to noise measurement).
While measuring the amount of noise present in the system and adjusting the system accordingly is an important aspect of maintaining good quality communications, it is also important that the entire system not be manipulated to compensate for problems being experienced by individual subscriber units.
Therefore, it is important to not only determine the noise level of a particular system, but to monitor the communication quality of individual subscriber units and determine if system wide adjustments are warranted.